Presently available diagnostic imaging apparatuses for capturing diagnostic images of patients include CT scanners, MRI (Magnetic Resonance Imaging) apparatuses, PET (Positron Emission Tomography) apparatuses, ultrasonic diagnostic apparatuses, CT angiography apparatuses, MRA (MR angiography) apparatuses and the like. When the abovementioned diagnostic imaging apparatuses are used, a liquid such as a contrast medium and physiological saline may be injected into a patient. Chemical liquid injectors for automatically performing the injection have been put into practical use.
Such a chemical liquid injector has a piston driving mechanism having a driving motor, a slider mechanism and the like, for example. A liquid syringe is removably mounted on the injector. The liquid syringe typically includes a cylinder member and a piston member slidably inserted in the cylinder member.
More specifically, the cylinder member is formed in a cylindrical shape, and has an opened trailing end and a closed leading end having a conduit formed at the center thereof. An annular cylinder flange is formed in the outer circumference of the trailing end of the cylinder member, and the piston member is slidably inserted into the cylinder member through the opening at the trailing end. The piston member is formed in a cylindrical shape and has an annular piston flange formed in the outer circumference of a trailing end.
There are a pre-filled type and a refill type in the liquid syringe. The liquid syringe of the pre-filled type includes a cylinder member filled with a liquid and is wholly sealed by a packing material for shipment. The liquid syringe of the refill type includes a cylinder member which can be filled with a desired liquid by a user. For simplicity, the following description will be made assuming that the liquid syringe of the pre-filled type is used.
When the liquid in the liquid syringe of the abovementioned type is injected into a patient, an operator prepares a liquid syringe containing an appropriate liquid and takes out the liquid syringe from the packing material. The operator connects the liquid syringe to a patient through an extension tube and mounts the liquid syringe on a chemical liquid injector. The cylinder flange is held by a cylinder holding mechanism. In this state, the chemical liquid injector presses the piston member into the cylinder member with a piston driving mechanism in accordance with a predetermined operation to inject the liquid into the patient from the liquid syringe.
The operator determines the rate at which the liquid is injected and the total quantity of the liquid to be injected in view of the type of the liquid and the like, and enters data representing the rate and total quantity into the chemical liquid injector. The chemical liquid injector injects the liquid into the patient based on the entered data. For example, if a contrast medium is injected as the liquid, the image contrast of the patient is changed to allow the diagnostic imaging apparatus to capture a favorable diagnostic image of the patient.
Some chemical liquid injectors can inject physiological saline as well as the contrast medium into the patient. In such a chemical liquid injector, the operator enters as desired an instruction to inject the physiological saline following the completion of the injection of the contrast medium, together with data representing the injection rate and total quantity of the physiological saline, into the chemical liquid injector. Based on the entered data, the chemical liquid injector first injects the contrast medium into the patient and then automatically injects the physiological saline. The subsequently injected physiological saline can push the previously injected contrast medium to reduce the consumption of the contrast medium and also can reduce artifacts in the captured image.
The contrast medium has a high viscosity, but the chemical liquid injector can insert the piston member into the cylinder member of the liquid syringe at high pressure and is preferably used for injection of the contrast medium. To insert the piston member into the cylinder member at high pressure, the cylinder member needs to be held securely.
Thus, a chemical liquid injector applied for patent by the applicant of the present application includes a pair of metallic flange holding members supported openably and closeably to hold individually the left and the right of a cylinder flange of a liquid syringe inserted from above (see, for example, non-patent document 1 below).
Non-patent document 1: “Dual Shot/A-300 in product guides of Nemoto Kyorindo Co., Ltd” (retrieved in Jun. 30, 2004) (URL:http://www.nemoto-do.co.jp/seihin_ct.html#dual)